CALGB 49907: Older women with breast cancer adherent to chemotherapy

Most women with breast cancer aged 65 years or older were adherent to short-term oral chemotherapy with capecitabine, according to the findings of an adherence companion study.

“As a greater number of oral medication are tested and made available for the treatment of patients with cancer, adherence has been recognized as an important consideration in interpreting outcome in both individual patients as well as in the context of clinical trials,” the researchers wrote.

Researchers enrolled 161 women from the Cancer and Leukemia Group B study (CALGB) 49907 into an adherence substudy (60104) to measure medication adherence and to examine the relationship between adherence and aging.

Patients were assigned capecitabine (Xeloda, Roche) in two divided doses daily for 14 days during a 21-day cycle for six cycles. Microelectronic monitoring system caps recorded pill bottle openings. Adherence was defined as taking at least 80% of expected doses as recorded by the microelectronic monitoring system.

Eighty-three percent of patients persisted with capecitabine to completion of the planned protocol. Among those not completing the planned protocol, reasons included toxicity, adverse effects, complications, study withdraw, disease progression, relapse and death.

Average adherence was 78% for all patients for all cycles; average adherence was not associated with the number of cycles (P=.41). Average adherence varied, with some patients taking less than 10% and many taking 100%.

Twenty-five percent of patients took less than 80% of expected doses. In multivariate analysis, those with node-positive disease (P=.01) and those who received partial mastectomy/lumpectomy/excisional biopsy (P=.01) were more likely to be adherent. Factors such as age, ethnicity and tumor size were not associated with adherence.

“Future clinical trials evaluating oral agents for the treatment of cancer should consider including rigorous measurement of adherence to improve understanding of the benefits and risks of any oral therapy for patients,” researchers said.

Partridge AH. J Clin Oncol. 2010;doi:10.1200/JCO.2009.26.4671.